Enzyme-linked immunosorbent assay (ELISA) is a commonly used protein analysis method based on immunological reaction, which can be used to detect and quantify antibodies, antigens, proteins, glycoproteins, etc. ELISA is based on the immobilization and the enzyme labeling of antigen/antibody. Both immobilized and enzyme-labeled antigens or antibodies can retain their immunological activity, while enzyme-labeled antigens or antibodies also have enzyme activity. The main method of the ELISA is to coat a known antigen or antibody on a multi-well plate, and the test specimen reacts with the antigen or antibody on the multi-well plate. Then the enzyme-labeled antigen or antibody is added, which are then bound to the multi-well plate through the reaction. The amount of enzyme on the multi-well plate is proportional to the amount of test substance in the specimen. After adding the substrate of the enzyme reaction, the substrate is catalyzed by the enzyme to become a color-developing product. The amount of these products is directly related to the amount of the test substance in the specimen, so qualitative or quantitative analysis can be carried out according to the degree of color.
|Coating the antigen on the multi-well plate, and then directly detect the antigen with enzyme-labeled antibody.|
|First coat the known antigen on the multi-well plate, then add the sample to be tested to specifically bind to the antigen. After washing, add enzyme-labeled antibody, and the substrate is used for color development.|
|Sandwich ELISA is mostly used to detect antigens. Firstly, the known antibody is coated on the multi-well plate, and then the sample to be tested is added to specifically bind to the antibody. After washing, the antibody that binds to different epitopes of the antigen is added for detection and the substrate is used for color development.|
|Competitive ELISA is to determine the content of the target analyte in the sample by quantifying the interference of the analyte on the reference antigen (or antibody) signal. Take the determination of antigen as an example. Firstly, the reference antigen is pre-coated on the multi-well plate. The antigen in the sample and the reference antigen are competitively combined with the enzyme-labeled antibody. After washing, perform the color test, and the color development result is inversely proportional to the concentration of the antigen in the sample.|
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